IB/cm: Fix sleeping while spin lock is held

In case of LAP are used for RoCE, it can lead to a problem of sleeping a
context while spin lock is held in below flow.

cm_lap_handler
	->spin_lock
	-> <..switch_case..>
	-> cm_init_av_for_response
		-> ib_init_ah_from_wc
			-> rdma_addr_find_l2_eth_by_grh
				wait_for_completion()

Therefore ah attribute initialization is done for incoming lap requests
outside of the lock context.
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/cm.c

@@ -3164,6 +3164,12 @@ static int cm_lap_handler(struct cm_work *work)
 	if (!cm_id_priv)
 		return -EINVAL;
 
+	ret = cm_init_av_for_response(work->port, work->mad_recv_wc->wc,
+				      work->mad_recv_wc->recv_buf.grh,
+				      &cm_id_priv->av);
+	if (ret)
+		goto deref;
+
 	param = &work->cm_event.param.lap_rcvd;
 	memset(&work->path[0], 0, sizeof(work->path[1]));
 	cm_path_set_rec_type(work->port->cm_dev->ib_device,
@@ -3210,11 +3216,6 @@ static int cm_lap_handler(struct cm_work *work)
 
 	cm_id_priv->id.lap_state = IB_CM_LAP_RCVD;
 	cm_id_priv->tid = lap_msg->hdr.tid;
-	ret = cm_init_av_for_response(work->port, work->mad_recv_wc->wc,
-				      work->mad_recv_wc->recv_buf.grh,
-				      &cm_id_priv->av);
-	if (ret)
-		goto unlock;
 	cm_init_av_by_path(param->alternate_path, &cm_id_priv->alt_av,
 			   cm_id_priv);
 	ret = atomic_inc_and_test(&cm_id_priv->work_count);